For purposes of communicating well fluid to a surface of a well, such as an oil or gas well, a well may include production tubing. Often times, to enhance the rate at which fluid is produced through the production tubing, an artificial-lift technique is employed. One such technique involves injecting gas into the production tubing to displace some of the well fluid in the tubing with lighter gas. The displacement of the well fluid with the lighter gas reduces the hydrostatic pressure inside the production tubing and allows reservoir fluids to enter the wellbore at a higher flow rate. The gas to be injected into the production tubing typically is conveyed down hole via an annulus and enters the production tubing through one or more gas lift barrier valves.
There are a number of problems that can develop in a producing well that can negatively affect operations, production and ultimately revenue generated, such as failure of mechanical equipment, changes in production characteristics, plugging and increases in injection pressure. After a well goes into production, these events may occur, requiring modification of the well in order to achieve optimal production; this is called well intervention. For example, in many older wells, gas lift systems cannot be used without removing the production tubing to place mandrels and valves. This is also the case in wells where the original gas lift systems are no longer functioning or functioning incorrectly. Coiled tubing has often been used in well intervention because the flexibility of the tubing allows the tubing to be placed into the well inside the already existing production tubing, thus, coiled tubing is often used as a retrofit to fix issues.
Gas lift assemblies attached to coiled tubing, such as the one disclosed in U.S. Pat. No. 5,170,815, are known in the art. Nevertheless, the known assemblies fail to offer flexibility in the choice of gas lift valve. Thus, in an effort to optimize a gas lift system, there exists a continuing need to provide gas lift in a flexible system, whereby older wells can be retrofitted with the appropriate valve for the application.